pbr sheen

packages/custom-material/src/advanced-shader/thinfilm/IridescenceIndirectLight.glsl

@@ -1,7 +1,7 @@
 #define FUNCTION_SPECULAR_IBL evaluateSpecularIBLIridescence
 #include "BRDF.glsl"
 #include "./IridescenceFunction.glsl"
-#include "LightProbe.glsl"
+#include "LightIndirectFunctions.glsl"
 
 void evaluateSpecularIBLIridescence(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData, float radianceAttenuation, inout vec3 specularColor){
 

packages/shaderlab/src/shaders/PBR.gs

@@ -47,33 +47,20 @@ Shader "PBR.gs" {
         material_IridescenceTexture("IridescenceTexture", Texture2D);
       }
 
+      Header("Sheen"){
+        UI_SheenIntensity("Intensity", Range(0, 1, 0.01)) = 0;
+        UI_SheenColor("Color", Color ) = (0, 0, 0, 0);
+        material_SheenRoughness("Roughness", Range(0, 1, 0.01)) = 0;
+        material_SheenTexture("ColorTexture", Texture2D);
+        material_SheenRoughnessTexture("RoughnessTexture", Texture2D);
+      }
+
       Header("Common") {
         material_AlphaCutoff( "AlphaCutoff", Range(0, 1, 0.01) ) = 0;
         material_TilingOffset("TilingOffset", Vector4) = (1, 1, 0, 0);
       }
     }
-
-    EditorMacros {
-      Header("Conditional Macors") {
-        MATERIAL_HAS_BASETEXTURE("HAS_BASETEXTURE");
-        MATERIAL_HAS_ROUGHNESS_METALLIC_TEXTURE("HAS_ROUGHNESS_METALLIC_TEXTURE");
-        MATERIAL_ENABLE_ANISOTROPY("ENABLE_ANISOTROPY");
-        MATERIAL_HAS_ANISOTROPY_TEXTURE("HAS_ANISOTROPY_TEXTURE")
-        MATERIAL_HAS_NORMALTEXTURE("HAS_NORMALTEXTURE");
-        MATERIAL_HAS_EMISSIVETEXTURE("HAS_EMISSIVETEXTURE");
-        MATERIAL_HAS_OCCLUSION_TEXTURE("HAS_OCCLUSION_TEXTURE");
-        MATERIAL_ENABLE_CLEAR_COAT("ENABLE_CLEAR_COAT");
-        MATERIAL_HAS_CLEAR_COAT_TEXTURE("HAS_CLEAR_COAT_TEXTURE");
-        MATERIAL_HAS_CLEAR_COAT_ROUGHNESS_TEXTURE("HAS_CLEAR_COAT_ROUGHNESS_TEXTURE");
-        MATERIAL_HAS_CLEAR_COAT_NORMAL_TEXTURE("HAS_CLEAR_COAT_NORMAL_TEXTURE");
-        MATERIAL_ENABLE_IRIDESCENCE("ENABLE_IRIDESCENCE");
-        MATERIAL_HAS_IRIDESCENCE_THICKNESS_TEXTURE("HAS_IRIDESCENCE_THICKNESS_TEXTURE");
-        MATERIAL_HAS_IRIDESCENCE_TEXTURE("HAS_IRIDESCENCE_TEXTURE");
-        MATERIAL_IS_TRANSPARENT("IS_TRANSPARENT");
-        MATERIAL_IS_ALPHA_CUTOFF("IS_ALPHA_CUTOFF");
-      }
-    }
-
+
     SubShader "Default" {
       UsePass "pbr/Default/ShadowCaster"
 

packages/shaderlab/src/shaders/shadingPBR/BRDF.glsl

@@ -56,6 +56,11 @@ struct SurfaceData{
         float iridescenceThickness;
     #endif
 
+    #ifdef MATERIAL_ENABLE_SHEEN
+        float sheenRoughness;
+        vec3  sheenColor;
+    #endif
+
 };
 
 
@@ -72,8 +77,15 @@ struct BRDFData{
     #ifdef MATERIAL_ENABLE_IRIDESCENCE
         vec3  iridescenceSpecularColor;
     #endif
+
+    #ifdef MATERIAL_ENABLE_SHEEN
+        float sheenRoughness;
+        float sheenEnergy;
+    #endif
+
 };
 
+#include "LightIndirectFunctions.glsl"
 
 float getAARoughnessFactor(vec3 normal) {
     // Kaplanyan 2016, "Stable specular highlights"
@@ -305,6 +317,31 @@ vec3 BRDF_Diffuse_Lambert(vec3 diffuseColor) {
     }
 #endif
 
+#ifdef MATERIAL_ENABLE_SHEEN
+    // http://www.aconty.com/pdf/s2017_pbs_imageworks_sheen.pdf
+    float D_Charlie(float roughness, float dotNH) {
+        float invAlpha  = 1.0 / roughness;
+        float cos2h = dotNH * dotNH;
+        float sin2h = max(1.0 - cos2h, 0.0078125); // 2^(-14/2), so sin2h^2 > 0 in fp16
+        return (2.0 + invAlpha) * pow(sin2h, invAlpha * 0.5) / (2.0 * PI);
+    }
+
+    // Neubelt and Pettineo 2013, "Crafting a Next-gen Material Pipeline for The Order: 1886".
+    float V_Neubelt(float NoV, float NoL) {
+        return saturate(1.0 / (4.0 * (NoL + NoV - NoL * NoV)));
+    }
+
+    vec3 sheenBRDF(vec3 incidentDirection, SurfaceData surfaceData, vec3 sheenColor, float sheenRoughness) {
+        vec3 halfDir = normalize(incidentDirection + surfaceData.viewDir);
+        float dotNL = saturate(dot(surfaceData.normal, incidentDirection));
+        float dotNH = saturate(dot(surfaceData.normal, halfDir));
+        float D = D_Charlie(sheenRoughness, dotNH);
+        float V = V_Neubelt(surfaceData.dotNV, dotNL);
+        vec3 F = sheenColor;
+        return  D * V * F;
+    }
+#endif
+
 void initBRDFData(SurfaceData surfaceData, out BRDFData brdfData){
     vec3 albedoColor = surfaceData.albedoColor;
     vec3 specularColor = surfaceData.specularColor;
@@ -332,6 +369,14 @@ void initBRDFData(SurfaceData surfaceData, out BRDFData brdfData){
         float topIOR = 1.0;
         brdfData.iridescenceSpecularColor = evalIridescenceSpecular(topIOR, surfaceData.dotNV, surfaceData.iridesceceIOR, brdfData.specularColor, surfaceData.iridescenceThickness);   
     #endif
+
+    #ifdef MATERIAL_ENABLE_SHEEN
+        brdfData.sheenRoughness = max(MIN_PERCEPTUAL_ROUGHNESS, min(surfaceData.sheenRoughness + getAARoughnessFactor(surfaceData.normal), 1.0));
+        // sheen energy compensation approximation calculation in ‘Sheen DFG LUT integrated over diffuse IBL’
+        // https://drive.google.com/file/d/1T0D1VSyR4AllqIJTQAraEIzjlb5h4FKH/view?usp=sharing
+        float IBLSheenDFG = IBLSheenDFG(surfaceData, brdfData.sheenRoughness);
+        brdfData.sheenScaling = 1.0 - IBLSheenDFG * max(max(surfaceData.sheenColor.r, surfaceData.sheenColor.g), surfaceData.sheenColor.b);
+    #endif
 }
 
 #endif

packages/shaderlab/src/shaders/shadingPBR/FragmentPBR.glsl

@@ -50,6 +50,18 @@ float material_OcclusionTextureCoord;
     #endif
 #endif
 
+#ifdef MATERIAL_ENABLE_SHEEN
+    float material_SheenRoughness;
+    vec3 material_SheenColor;
+    #ifdef MATERIAL_HAS_SHEEN_TEXTURE
+       sampler2D material_SheenTexture;
+    #endif
+
+    #ifdef MATERIAL_HAS_SHEEN_ROUGHNESS_TEXTURE
+       sampler2D material_SheenRoughnessTexture;
+    #endif
+#endif
+
 // Texture
 #ifdef MATERIAL_HAS_BASETEXTURE
     sampler2D material_BaseTexture;
@@ -263,6 +275,23 @@ SurfaceData getSurfaceData(Varyings v, vec2 aoUV, bool isFrontFacing){
         #endif
     #endif
 
+    #ifdef MATERIAL_ENABLE_SHEEN
+        vec3 sheenColor = material_SheenColor;
+        #ifdef MATERIAL_HAS_SHEEN_TEXTURE
+            vec4 sheenTextureColor = texture2D(material_SheenTexture, uv);
+            #ifndef ENGINE_IS_COLORSPACE_GAMMA
+                sheenTextureColor = gammaToLinear(sheenTextureColor);
+            #endif
+            sheenColor *= sheenTextureColor.rgb;
+        #endif
+        surfaceData.sheenColor = sheenColor;
+
+        surfaceData.sheenRoughness = material_SheenRoughness;
+        #ifdef MATERIAL_HAS_SHEEN_ROUGHNESS_TEXTURE
+            surfaceData.sheenRoughness *= texture2D(material_SheenRoughnessTexture, uv).a;
+        #endif
+    #endif
+
     // AO
     float diffuseAO = 1.0;
     float specularAO = 1.0;

packages/shaderlab/src/shaders/shadingPBR/LightDirectPBR.glsl

@@ -14,6 +14,9 @@
 #ifndef FUNCTION_CLEAR_COAT_LOBE
     #define FUNCTION_CLEAR_COAT_LOBE clearCoatLobe
 #endif
+#ifndef FUNCTION_SHEEN_LOBE
+    #define FUNCTION_SHEEN_LOBE SheenLobe
+#endif
 
 #include "BRDF.glsl"
 #include "Light.glsl"
@@ -34,6 +37,8 @@ void surfaceShading(Varyings varyings, SurfaceData surfaceData, BRDFData brdfDat
     FUNCTION_DIFFUSE_LOBE(varyings, surfaceData, brdfData, attenuationIrradiance, diffuseColor);
     // Specular Lobe
     FUNCTION_SPECULAR_LOBE(varyings, surfaceData, brdfData, incidentDirection, attenuationIrradiance, specularColor);
+    //  Lobe
+    FUNCTION_SHEEN_LOBE(varyings, surfaceData, brdfData, incidentDirection, attenuationIrradiance, diffuseColor, specularColor);
 
     color += diffuseColor + specularColor;
 

packages/shaderlab/src/shaders/shadingPBR/LightProbe.glsl → packages/shaderlab/src/shaders/shadingPBR/LightIndirectFunctions.glsl

@@ -1,8 +1,7 @@
-#ifndef LIGHT_PROBE
-#define LIGHT_PROBE
-
+#ifndef LIGHT_INDIRECT_FUNCTIONS_INCLUDED
+#define LIGHT_INDIRECT_FUNCTIONS_INCLUDED
+#include "Light.glsl"
 // ------------------------Specular------------------------
-
 // ref: https://www.unrealengine.com/blog/physically-based-shading-on-mobile - environmentBRDF for GGX on mobile
 vec3 envBRDFApprox(vec3 specularColor, float roughness, float dotNV ) {
 
@@ -68,4 +67,16 @@ vec3 getLightProbeRadiance(SurfaceData surfaceData, vec3 normal, float roughness
     #endif
 }
 
+// This is a curve-fit approxmation to the "Charlie sheen" BRDF integrated over the hemisphere from
+// Estevez and Kulla 2017, "Production Friendly Microfacet Sheen BRDF". The analysis can be found
+// in the Sheen section of https://drive.google.com/file/d/1T0D1VSyR4AllqIJTQAraEIzjlb5h4FKH/view?usp=sharing
+float IBLSheenDFG(SurfaceData surfaceData, float roughness) {
+    float dotNV = surfaceData.dotNV;
+    float r2 = roughness * roughness;
+    float a = roughness < 0.25 ? -339.2 * r2 + 161.4 * roughness - 25.9 : -8.48 * r2 + 14.3 * roughness - 9.95;
+    float b = roughness < 0.25 ? 44.0 * r2 - 23.7 * roughness + 3.26 : 1.97 * r2 - 3.27 * roughness + 0.72;
+    float DG = exp( a * dotNV + b ) + ( roughness < 0.25 ? 0.0 : 0.1 * ( roughness - 0.25 ) );
+    return saturate( DG * RECIPROCAL_PI );
+}
+
 #endif

packages/shaderlab/src/shaders/shadingPBR/LightIndirectPBR.glsl

@@ -11,10 +11,12 @@
 #ifndef FUNCTION_CLEAR_COAT_IBL
     #define FUNCTION_CLEAR_COAT_IBL evaluateClearCoatIBL
 #endif
-
+#ifndef FUNCTION_SHEEN_IBL
+    #define FUNCTION_SHEEN_IBL evaluateSheenIBL
+#endif
 #include "BRDF.glsl"
 #include "Light.glsl"
-#include "LightProbe.glsl"
+#include "LightIndirectFunctions.glsl"
 
 // ------------------------Diffuse------------------------
 
@@ -77,6 +79,15 @@ void evaluateSpecularIBL(Varyings varyings, SurfaceData surfaceData, BRDFData br
     outSpecularColor += surfaceData.specularAO * radianceAttenuation * radiance * envBRDFApprox(speculaColor, brdfData.roughness, surfaceData.dotNV);
 }
 
+void evaluateSheenIBL(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData,  float radianceAttenuation, inout vec3 diffuseColor, inout vec3 specularColor){
+    #ifdef MATERIAL_ENABLE_SHEEN
+        diffuseColor *= brdfData.sheenScaling;
+        specularColor *= brdfData.sheenScaling;
+
+    vec3 reflectance = radianceAttenuation * IBLSheenDFG(surfaceData, brdfData.sheenRoughness) * surfaceData.sheenColor;
+    specularColor += reflectance;
+    #endif
+}
 
 void evaluateIBL(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData, inout vec3 color){
     vec3 diffuseColor = vec3(0);
@@ -90,8 +101,12 @@ void evaluateIBL(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData,
 
     // IBL specular
     FUNCTION_SPECULAR_IBL(varyings, surfaceData, brdfData, radianceAttenuation, specularColor);
-
+
+    // IBL sheen
+    FUNCTION_SHEEN_IBL(varyings, surfaceData, brdfData, radianceAttenuation, diffuseColor, specularColor);
+
     color += diffuseColor + specularColor;
+
 }
 
 

packages/shaderlab/src/shaders/shadingPBR/ReflectionLobe.glsl

@@ -6,7 +6,16 @@ void diffuseLobe(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData,
 }
 
 void specularLobe(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData, vec3 incidentDirection, vec3 attenuationIrradiance, inout vec3 specularColor){
-    specularColor += attenuationIrradiance *  BRDF_Specular_GGX( incidentDirection, surfaceData, brdfData, surfaceData.normal, brdfData.specularColor, brdfData.roughness);
+        specularColor += attenuationIrradiance *  BRDF_Specular_GGX( incidentDirection, surfaceData, brdfData, surfaceData.normal, brdfData.specularColor, brdfData.roughness);
+}
+
+void SheenLobe(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData, vec3 incidentDirection, vec3 attenuationIrradiance, inout vec3 diffuseColor, inout vec3 specularColor){
+    #ifdef MATERIAL_ENABLE_SHEEN
+        diffuseColor *= brdfData.sheenScaling;
+        specularColor *= brdfData.sheenScaling;
+
+        specularColor += attenuationIrradiance * sheenBRDF(incidentDirection, surfaceData, surfaceData.sheenColor, brdfData.sheenRoughness);
+    #endif
 }
 
 float clearCoatLobe(Varyings varyings, SurfaceData surfaceData, BRDFData brdfData, vec3 incidentDirection, vec3 color, inout vec3 specularColor){
@@ -16,7 +25,7 @@ float clearCoatLobe(Varyings varyings, SurfaceData surfaceData, BRDFData brdfDat
         float clearCoatDotNL = saturate( dot( surfaceData.clearCoatNormal, incidentDirection ) );
         vec3 clearCoatIrradiance = clearCoatDotNL * color;
 
-        specularColor += surfaceData.clearCoat * clearCoatIrradiance * BRDF_Specular_GGX( incidentDirection, surfaceData, surfaceData.clearCoatNormal, brdfData.clearCoatSpecularColor, brdfData.clearCoatRoughness );
+        specularColor += surfaceData.clearCoat * clearCoatIrradiance * BRDF_Specular_GGX( incidentDirection, surfaceData, brdfData, surfaceData.clearCoatNormal, brdfData.clearCoatSpecularColor, brdfData.clearCoatRoughness );
         attenuation -= surfaceData.clearCoat * F_Schlick(0.04, surfaceData.clearCoatDotNV);
     #endif
 

packages/shaderlab/src/shaders/shadingPBR/index.ts

@@ -1,6 +1,6 @@
 import AttributesPBR from "./AttributesPBR.glsl";
 import BRDF from "./BRDF.glsl";
-import LightProbe from "./LightProbe.glsl";
+import LightIndirectFunctions from "./LightIndirectFunctions.glsl";
 import ForwardPassPBR from "./ForwardPassPBR.glsl";
 import FragmentPBR from "./FragmentPBR.glsl";
 import LightDirectPBR from "./LightDirectPBR.glsl";
@@ -18,6 +18,6 @@ export default [
   { source: LightIndirectPBR, includeKey: "LightIndirectPBR.glsl" },
   { source: VertexPBR, includeKey: "VertexPBR.glsl" },
   { source: BRDF, includeKey: "BRDF.glsl" },
-  { source: LightProbe, includeKey: "LightProbe.glsl" },
+  { source: LightIndirectFunctions, includeKey: "LightIndirectFunctions.glsl" },
   { source: ReflectionLobe, includeKey: "ReflectionLobe.glsl" }
 ];